Types of Tumors

Benign Tumors

Benign tumors are abnormal growths that are no longer under normal regulation. They grow slowly, resemble normal cells, and are not cancerous. They grow only in one place and cannot spread or invade other parts of the body. They can however become harmful if they press on vital organs. Examples of benign tumors include skin moles, lipomas, hepatic adenomas.

Malignant Tumors

These tumors are composed of embryonic, primitive, or poorly differentiated cells. They grow in a rapid, disorganized manner that is harmful to the body. They can also invade surrounding tissues and are become metastatic, initiating the growth of similar tumors in distant organs.

Cancer Types Based on Cell Genesis

Cancers can be classified based on cell origin.

Cancer Grading and Staging


Cancer staging (illustrated on the right for colon cancer) describes the extent of a person's cancer based on:

  1. The site of the primary tumor.
  2. Its size
  3. How far it has invaded into local tissues and structures
  4. Whether it has spread to regional lymph nodes.
  5. Whether is has metastasized to other regions of the body.

For additional information see the National Cancer Institute web page on Cancer Staging.


The microscopic appearance a cancer indicates its likely behavior and its responsiveness to treatment.

How Does Cancer Kill?


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